‘We can have cows and a clean conscience’

New Zealand can farm cows and still have a clear climate conscience by shaving about 10-22 percent off its methane emissions, a new report for the Parliamentary Commissioner for the Environment’s office has found. Eloise Gibson reports.

The promising news for the nation’s farmers is that while such cuts would be a big ask, they might still be compatible with being an agriculture-heavy nation.

Deeper cuts to achieve a total 20-27 percent reduction in the methane burped by our farm animals would be needed by 2100 for New Zealand to be able to say its livestock were not worsening climate change with methane. But farms could keep producing some methane forever without adding heat to the atmosphere.

On the other hand, if New Zealand keeps making as much methane as it was in 2016, at the last count, warming would get about 10-20 percent worse.

Farms make up about half of New Zealand’s emissions, mostly in the form of methane burped from cows’ and, to a lesser extent, sheep’s digestive tracts.

What to do about methane has been a feature of the debate about the Zero Carbon Bill: it’s a much shorter-lived gas than Co2, but also more potent in the short-term. New feed additives, vaccines, breeding tactics and other measures show some promise at reducing livestock methane, but not cutting it to zero, barring a mass reduction in cows.

The government’s consultation document mooted three paths to reduce emissions: reducing all emissions to net zero by 2050, reducing Co2 to net zero whilst keeping methane “stable”, or cutting carbon to zero while setting no goal for reducing methane.

The compromise option

The middle option of stabilizing short-lived gases such as methane could be seen as the compromise option, given the need for cross-party support and New Zealand’s heavy emissions of methane per-capita, and therefore as the most likely path to be adopted.

But the government’s discussion document didn’t give any hints as to the level at which methane might be stabilized. That number is crucial.

The environment commissioner, Simon Upton, noted when he released today’s report: “The government has provided no indication of the level at which methane emissions might be stabilised under this option, or the amount of warming that might follow from stabilization,” he said. “Indeed, the rationale behind such a ‘split gas’ target was missing.”

The modelling released by Upton’s office was done by climate and agriculture expert Andy Reisinger and tallies methane’s past and future contribution to climate change as well as what would be needed to be warming-neutral, ahead of a fuller report on livestock emissions later this year.

Farmers do have to do something

Reisinger’s calculations concluded it would take more than merely continuing to clock up efficiency gains in farm productivity to keep farm’s climate contribution neutral. And holding livestock emissions steady at 2016’s rate would clearly not be enough to avoid contributing to a hotter planet.

Importantly, the calculations rely on what other countries do.

Paradoxically, the report says that the more that other countries cut emissions, the more we need to reduce methane to avoid being responsible for making matters worse.

For example, the 22 per cent level of reduction in methane in 2050 reflects a scenario in which other countries take strong action and meet the Paris Agreement goals. The 10 per cent level reflects a scenario in which other countries take some action, but not enough to achieve the Paris Agreement goals.

“This modelling tells us that if other countries take strong and rapid action to meet the ‘well-below 2°C’ goal, New Zealand’s emissions of methane from livestock would need to be reduced by about 22 per cent to avoid additional warming. This is because the background concentrations of methane will be lower if other countries take strong action, so the methane emitted by New Zealand causes more warming,” says the report.

“If, on the other hand, we assume that other countries take some action on climate change, but not enough to achieve the well-below 2°C goal, New Zealand’s emissions of livestock methane would need to be reduced by 12 about 10 per cent to achieve the same temperature objective.”

“Given that the Zero Carbon Bill is intended to be aligned with the Paris Agreement, an assumption that other countries will act to achieve its goals seems appropriate,” it says.

“….[But] In reality, the trajectory for livestock methane [of a 20 percent reduction] is unlikely to follow this course. If deep reductions early on are not possible, then a steeper reduction to a lower emission level in 2050 would be required.”

The report notes it is not a policy recommendation by Upton, but it is designed to support discussion of the Zero Carbon bill by supplying more evidence.

The consultation attracted about 15,000 submissions, which are being considered now, according to Eugenie Sage’s office.
Because of methane’s short term potency, it has an outsized impact on the warming the planet has already experienced.

40 percent of global warming

Globally, it has contributed 40 per cent of total global warming since 1750, though, long-term, CO2 will be by far the biggest enduring problem. When it comes to New Zealand’s impact on total warming up to 2016 (the latest year for which greenhouse gas data is available), the amount attributable to New Zealand’s historical livestock methane emissions is about twice as large as the warming from historical fossil carbon dioxide emissions.

But the warming from carbon dioxide is currently increasing about twice as fast.

The two gases also interact in ways that make the total impact worse.

For example, the report says, “a warmer climate causes any carbon dioxide already in the atmosphere to remain there for longer, and more carbon dioxide to be released from oceans and the biosphere. These changes amplify and prolong the warming caused directly by the emission of methane (or any other greenhouse gas).

While there is uncertainty regarding the magnitude of these feedbacks, there is robust evidence that they result in additional warming, and that this warming can be significant over time.”

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